The present invention relates to the sterilization arts. It finds particular application in conjunction with the assessment of evacuation in vaporized hydrogen peroxide sterilization systems, and will be described with particular reference thereto. It should be appreciated, however, that the invention is also applicable to other processes where evacuation is monitored on a frequent basis.
Sterilization and reuse of instruments has proved to be a valuable means of cutting the costs of delivering health care. Hydrogen peroxide vapor is a particularly useful sterilant for instruments because of its effectiveness at low temperatures, which avoids destruction of heat-sensitive medical instruments. In addition, it decomposes to water and oxygen, which are not harmful and do not pose disposal problems.
In use, hydrogen peroxide vapor is mixed with water vapor. At the temperatures employed for hydrogen peroxide sterilization, the water vapor does not act as an effective sterilant. Because it diffuses more rapidly into narrow lumens and other difficult to reach areas of instruments than hydrogen peroxide vapor, the effectiveness of hydrogen peroxide as a sterilant is often reduced by the presence of water vapor. Moreover, condensed water acts as a shield for microorganisms beneath its surface, further reducing the effectiveness of the sterilant.
Evacuation of the sterilizer at various times throughout the sterilization process has been shown to overcome these problems and result in effective sterilization of even the most challenging of instruments. Cyclic evacuation during a cycle tends to pump the vapor down lumens and narrow passages. Evacuation of the sterilization chamber prior to a sterilization cycle also permits the sterilant to diffuse rapidly throughout the chamber and allows greater concentrations of sterilant to be achieved at a given pressure. This increases the rate of contact of the sterilant with the instruments, thereby reducing the time required for effective sterilization.
Since the effectiveness of sterilization depends heavily on the ability of the sterilizer to draw a sufficiently low vacuum, it is important to monitor the sterilizer for leaks on a regular basis, preferably at least once a day. Pressures as low as about 0.5 Torr are currently employed in commercial hydrogen peroxide vapor sterilization systems. Regular confirmatory monitoring assures that the purported sterilization has occurred, or at least that there was not a failure.
Current methods of monitoring the pressure reached within a sterilization chamber involve the use of fairly expensive equipment which, although accurately monitoring operational parameters, often does not provide an easy to read check on the adequacy of the vacuum.
The present invention provides a new and improved device for air removal testing of sterilization or disinfection systems which overcomes the above-referenced problems and others.